1. Field of the Invention
This invention relates generally to internal expansion engines and, more specifically, to engines where a non-combusting operating fluid is vaporized within a cylinder or cylinders, and where that vapor is expanded to perform mechanical work. In as much as no combustion is involved in engine operation, the invention will operate without an atmospheric inlet, and will emit no combustion products or effluent other than vapor of the working fluid. The engine can operate in a closed cycle, permitting use, for example, underwater or in a vacuum. Closed cycle construction is, however, not necessary for proper functioning. The preferred embodiment of the invention is an electrically-driven torque-generating device which has substantial start-up torque available with minimal standby power input requirements.
2. Description of the Prior Art
In the past, shaft power has been widely utilized as a motive force, since at least the introduction of the water wheel. Subsequently, various steam expansion engines were developed, which utilized external combustion sources to provide heated steam. The steam was expanded through a reciprocating piston linkage, or a turbine, to provide a shaft power output. Steam engines had inherent problems, however, in that the external boiler had to be fired substantially before shaft power could be produced.
Electric motors were also developed, and utilized the interaction of moving electromagnetic fields to provide a shaft power output. While various designs for such electric motors were developed, a problem common to each was the relatively low starting torque available.
Internal combustion engines, of both the spark ignition and compression ignition types, were also developed to provide shaft power sources which could be started quickly, consume minimal standby power and could produce substantial torque from a standing start. However, such internal combustion engines presented their own accompanying set of problems, including the local output of atmospheric pollutants in the form of the products of combustion, and the necessity for a continuing replacement of the fuel consumed in operation.
A need existed for an engine or other source of shaft power which: (1) did not require preheating a boiler; (2) did not require that a boiler be kept fired on a standby basis to provide a prompt startup capability; (3) did have substantial torque available from startup; (4) operated in a closed cycle, or in the alternative at least without local combustion product pollutant output; (5) consumed only minimal if any energy under standby conditions; and (6) did not require an input of fuel.